This invention relates to a trip device employed to discontinue operation of a machine upon the occurrence of an undesirable operating condition.
It is well known to those skilled in the art that machines such as turbomachinery and other similar rotating devices, require protection to prevent such machinery from continued operation upon the occurrence of an undesirable operating condition. Various types of trip devices have heretofore been employed to initiate the desired stoppage of operation of the machine. For example, it is desirable to prevent a rotating machine from continued operation upon a thrust bearing failure or upon the occurrence of excessive wear of the thrust bearing whereby undesirable axial clearances are developed. Typically, a trip device is installed upon the shaft of the rotating machine whereby the trip device will initiate the stoppage of the machine upon the occurrence of the excessive axial clearance.
Once the trip device has performed its desired function and the machine is either stopped or an alarm sounded, it is desirable that the various operating arms of the device be maintained in positions whereby no damage thereto will occur. For example, in a trip device having a separate sensing member movable upon the occurrence of the undesirable operating condition, it is desirable that any trip mechanism brought into contact with the sensing element be thereafter maintained in spaced apart relation thereto once a trip signal has been generated. This decreases maintenance required to insure proper operation of the device, as well as increases the reliability thereof. Furthermore, it is desirable that the trip device be maintained in a tripped condition once the undesirable condition has developed. This insures that supervisory or maintenance personnel are alerted to the problem or malfunction.